Preparation method of modified carbon five petroleum resin emulsion and application thereof

Abstract

This invention relates to the field of polymer emulsion polymerization and adhesives, specifically to a method for preparing a modified C5 petroleum resin emulsion and its application. The method involves heating C5 petroleum resin, adding a plasticizer and emulsifier, stirring until homogeneous, and then cooling. A shell monomer solution is then added and stirred until homogeneous, resulting in a mixture of molten resin and shell monomers. A protective colloid aqueous solution is slowly added to the molten resin and shell monomer mixture, and the stirring speed is increased to induce phase inversion emulsification. After the phase inversion occurs, deionized water is added, and stirring continues to form a primary emulsion. The primary emulsion is heated under inert gas protection, maintained at this temperature, cooled, and the pH value is adjusted. The mixture is then filtered to obtain the modified C5 petroleum resin emulsion. The emulsion obtained by this invention, when used in pressure-sensitive adhesives, can improve initial tack and peel strength while maintaining high holding power, and improves high-temperature holding performance and reduces peel residue.

Description

Technical Field

[0001] This invention relates to the field of polymer emulsion polymerization and adhesives, specifically to a method for preparing a modified C5 petroleum resin emulsion and its application. Background Technology

[0002] Water-based pressure-sensitive adhesives are widely used in labels, tapes, protective films, and medical dressings due to their advantages such as being environmentally friendly and non-toxic, safe to apply, and low in energy consumption. Water-based acrylic pressure-sensitive adhesives are currently the most widely used type of water-based pressure-sensitive adhesive. They are produced by emulsion polymerization of acrylic monomers and possess excellent weather resistance, transparency, and adhesive properties. However, pure acrylic pressure-sensitive adhesives suffer from insufficient initial tack, poor wettability on low surface energy substrates, and a difficulty in simultaneously achieving both cohesive strength and surface tack. Therefore, modification with tackifying resins is usually required.

[0003] C5 petroleum resin is a thermoplastic oligomer polymerized from the C5 fraction of ethylene cracking. It has the characteristics of wide availability, low price, and excellent water and chemical resistance, and is a commonly used tackifying resin in the pressure-sensitive adhesive industry. However, traditional solid C5 petroleum resin is insoluble in water and is difficult to add directly to water-based pressure-sensitive adhesive systems. Existing technologies mostly use external emulsifiers to emulsify C5 petroleum resin into an aqueous dispersion for addition, but there are the following problems: (1) The amount of emulsifier used is large, and the free emulsifier will migrate to the surface of the adhesive layer to form a weak interface layer, which leads to a decrease in the water resistance and peel strength of the pressure-sensitive adhesive; (2) C5 petroleum resin is a thermoplastic linear molecule. Although the addition can improve the initial tack, it will significantly reduce the cohesive strength of the adhesive layer, which manifests as a decrease in holding power, high-temperature overflow, peel residue and other problems; (3) The solid content of traditional C5 resin emulsion is usually less than 55%. When the solid content is increased, the viscosity increases sharply, making construction difficult.

[0004] Therefore, developing a modified C5 petroleum resin emulsion that combines high solids content, low viscosity, high tackification efficiency, and does not affect the cohesive strength of pressure-sensitive adhesives has significant industrial application value. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing modified C5 petroleum resin emulsion and its application.

[0006] The technical solution of the present invention is as follows: A method for preparing a modified C5 petroleum resin emulsion includes the following steps: C5 petroleum resin is heated to a molten state, plasticizer and emulsifier are added, stirred evenly and cooled, then shell monomer solution is added and stirred evenly to obtain a mixture of molten resin and shell monomer; wherein, the shell monomer solution includes monomer and initiator; A protective colloid aqueous solution is slowly added to the mixture of molten resin and shell monomer, and the stirring speed is increased to carry out phase transition emulsification. After the system undergoes phase transition, deionized water is added and stirring is continued to form a primary emulsion. The protective colloid aqueous solution includes polyvinyl alcohol. The primary emulsion was heated under inert gas protection, kept at that temperature for reaction, cooled, and then the pH value was adjusted and filtered to obtain a modified C5 petroleum resin emulsion.

[0007] It should be noted that in this invention, emulsifiers, plasticizers, and shell monomers are added to the molten state of C5 petroleum resin, allowing the shell monomers to be pre-distributed in the molten phase of the C5 petroleum resin and its interfacial region. Subsequently, phase reversal emulsification is performed using a protective colloidal aqueous solution containing polyvinyl alcohol, transforming the molten resin phase into dispersed latex particles in the aqueous phase. Then, through a heating and holding reaction, acrylate monomers undergo in-situ polymerization on the surface or near the surface of the C5 petroleum resin latex particles. Thus, a polyacrylate interfacial coating phase is formed on the outer side of the C5 petroleum resin latex particles, rather than simply forming a conventional resin emulsion dispersion.

[0008] In the above structure, the C5 petroleum resin has a thickening effect, while the polyacrylate shell phase has interfacial compatibility and coating effects. Because the shell phase has good compositional similarity to the waterborne acrylate pressure-sensitive adhesive matrix, it can improve the dispersion state of the C5 petroleum resin latex particles in the acrylate adhesive layer and reduce the possibility of C5 petroleum resin being directly exposed on the adhesive layer surface or bonding interface. Therefore, this interfacial coating structure can alleviate the problems of easy migration of resin components and weakening of the cohesive retention capacity of the adhesive layer in ordinary C5 petroleum resin emulsions.

[0009] Furthermore, the C5 petroleum resin includes hydrogenated C5 petroleum resin and / or modified C5 petroleum resin, wherein the softening point of the hydrogenated C5 petroleum resin is 100-125°C.

[0010] Furthermore, the plasticizer includes one or more of dibutyl phthalate, tributyl acetyl citrate, tributyl citrate, epoxidized soybean oil, hydrogenated naphthenic oil, polyether ester plasticizers, and low molecular weight polyisobutylene.

[0011] Furthermore, the emulsifier includes one or more of Span-80, Tween-80, sodium dodecyl sulfate, and reactive emulsifiers.

[0012] It should be noted that reactive emulsifiers are introduced in some embodiments of the present invention to reduce the free migration problem of ordinary small molecule emulsifiers. Ordinary emulsifiers mainly exist in a free state or a physically adsorbed state, and are prone to migrate to the surface of the adhesive layer or the bonding interface after film formation. Reactive emulsifiers contain unsaturated structures that can participate in free radical polymerization, and can partially participate in the latex particle interface polymerization during the shell polymerization process, or be more stably fixed near the latex particle interface, thereby reducing the adverse effects of free emulsifiers on the bonding interface.

[0013] Furthermore, the reverse emulsification is performed under ultrasonic conditions, with an ultrasonic power of 100-800W and an ultrasonic time of 5-60min.

[0014] A preferred method for preparing modified C5 petroleum resin includes the following steps: The C5 petroleum resin is heated to a molten state, and maleic anhydride and an initiator are added under inert gas protection. The reaction is carried out at 150-190℃ for 1-4 hours. After the reaction is completed, the resin is subjected to reduced pressure treatment at 140-150℃ to obtain the modified C5 petroleum resin.

[0015] It should be noted that maleic anhydride was used to lightly graft C5 petroleum resin, introducing a small amount of anhydride groups and / or carboxyl groups into the originally hydrophobic and less reactive C5 petroleum resin. This modification aims to provide polar sites on the core phase surface that can participate in interfacial interactions, further transforming the ordinary physical coating between the C5 petroleum resin core phase and the polyacrylate shell phase into a coating structure with stronger interfacial interactions.

[0016] Preferably, the initiator is one or more of dicumyl peroxide, benzoyl peroxide, azobisisobutyronitrile, and di-tert-butyl peroxide.

[0017] Furthermore, the monomer includes one or more of butyl acrylate, methyl methacrylate, glycidyl methacrylate, and hydroxyethyl methacrylate.

[0018] It should be noted that the introduction of glycidyl methacrylate and / or hydroxyethyl methacrylate into the shell monomer introduces epoxy and / or hydroxyl functional sites into the polyacrylate shell. These functional sites can form polar interactions, hydrogen bonds, or stronger interfacial bonds with the anhydride and / or carboxyl groups in maleic anhydride-grafted C5 petroleum resin, thereby enhancing the bonding stability between the core and shell phases. This structure helps reduce the migration tendency of the C5 petroleum resin core phase during film formation and use.

[0019] Furthermore, the mass ratio of Span-80, Tween-80, and sodium dodecyl sulfate is (1-2):(1-2):(0.5-1).

[0020] A pressure-sensitive adhesive, wherein the raw materials of the pressure-sensitive adhesive include at least one of modified C5 petroleum resin emulsion, acrylate copolymer emulsion, wetting agent, and defoamer, wherein the modified C5 petroleum resin emulsion is prepared according to the preparation method of the modified C5 petroleum resin emulsion.

[0021] It should be noted that traditional C5 petroleum resin emulsions are prone to problems such as increased particle size, increased viscosity, and decreased storage stability when the solid content is increased, making it difficult to simultaneously achieve high solid content, low viscosity, and good workability. Although existing core-shell or coated tackifying resin emulsions can improve the compatibility between C5 petroleum resin and waterborne acrylic pressure-sensitive adhesives to some extent, if the core C5 petroleum resin itself is still an inert hydrophobic resin and the shell polymer exists only through physical coating, the C5 petroleum resin may still migrate during the film formation, aging, or high-temperature use of the pressure-sensitive adhesive, resulting in residual adhesive, overflow adhesive, and decreased holding power.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects: (1) In this invention, C5 petroleum resin is heated and melted, then mixed with plasticizer, emulsifier and shell monomer solution, and then a protective colloid aqueous solution containing polyvinyl alcohol is added for reverse emulsification. The reaction is carried out under inert gas protection, so that the shell monomer polymerizes on the surface or near the surface of the C5 petroleum resin latex particles. As a result, C5 petroleum resin no longer exists only in the form of ordinary emulsion dispersion, but forms a polyacrylate interfacial coating phase on its outer side, thereby improving the compatibility and dispersion stability between C5 petroleum resin and waterborne acrylate pressure-sensitive adhesive system.

[0023] (2) The modified C5 petroleum resin emulsion prepared by this invention has a core-shell structure or an interfacial coating structure. The solid content of the emulsion can reach 55-65%, the viscosity at 25°C is less than 1000 mPa·s, the particle size distribution is relatively stable, and it has good dispersion stability and workability. Compared with ordinary C5 petroleum resin emulsions, the emulsion obtained by this invention is easier to disperse in aqueous acrylate copolymer emulsions and is less prone to obvious stratification, agglomeration, or excessively high workability, which is beneficial to improving the uniformity of adhesive coating and film stability.

[0024] (3) In this invention, the C5 petroleum resin, as the core phase, provides a thickening effect, while the polyacrylate copolymer, as the shell phase, forms an interfacial coating phase on or near the surface of the C5 petroleum resin latex particles, thereby improving the compatibility between the C5 petroleum resin and the waterborne acrylic pressure-sensitive adhesive system. When the emulsion of this invention is used in waterborne acrylic pressure-sensitive adhesives, it can improve the initial tack and 180° peel strength while maintaining the tack retention properties of the adhesive layer, avoiding the problems of decreased tack and severe adhesive residue that are easily caused by ordinary C5 resin emulsions.

[0025] (4) The modified C5 petroleum resin emulsion and acrylate copolymer emulsion obtained in this invention have good blending stability. After blending, the adhesive is not prone to obvious stratification or agglomeration, which is conducive to the formation of a more uniform adhesive film. Since the polyacrylate shell has a certain coating effect on the C5 petroleum resin core phase, it can reduce the tendency of C5 petroleum resin to migrate directly to the adhesive layer surface or bonding interface, thereby improving the cohesive retention ability of the adhesive layer and the residual adhesive after peeling.

[0026] (5) In the preferred embodiment, when the modified C5 petroleum resin emulsion prepared using the basic scheme of the present invention is used in water-based acrylic pressure-sensitive adhesive, the initial tack and 180° peel strength of the adhesive layer are significantly higher than those of the control sample without tackification, and the holding power can be maintained for more than 48 hours. Compared with commercially available ordinary non-core-shell C5 resin emulsions, the adhesive layer obtained by the present invention maintains a high tackification effect while significantly reducing residual adhesive, indicating that the interface coating structure of the present invention can effectively improve the problem that traditional C5 resin emulsions tackify but easily sacrifice cohesive retention performance.

[0027] (6) In a further improvement, the present invention employs maleic anhydride to lightly graft hydrogenated C5 petroleum resin, thereby introducing a small amount of anhydride groups and / or carboxyl groups into the C5 petroleum resin. When this modified C5 petroleum resin serves as the core phase, it can enhance the polar interaction and interfacial bonding force between itself and the polyacrylate shell phase, thereby further reducing the migration tendency of C5 petroleum resin in the adhesive layer and improving the adhesive layer's holding power, high-temperature holding power, and anti-residue properties.

[0028] (7) In a further improved scheme, glycidyl methacrylate and / or hydroxyethyl methacrylate are added to the shell monomer to make the resulting polyacrylate shell contain epoxy and / or hydroxyl functional sites. This functionalized shell can improve the bonding force between the polyacrylate shell phase and the maleic anhydride-grafted C5 petroleum resin core phase, and improve the compatibility between the modified C5 petroleum resin emulsion and the acrylate copolymer emulsion, thereby further improving the room temperature holding power, 70℃ holding power and post-peel residue resistance of the pressure-sensitive adhesive.

[0029] (8) In a further improved scheme, a reactive emulsifier is introduced into the emulsifier system. Reactive emulsifiers can participate in the interfacial polymerization of latex particles or be fixed at the latex particle interface. Compared to ordinary small-molecule emulsifiers, they have a lower tendency to migrate freely, which helps reduce the weak interface problems caused by the migration of free emulsifiers to the adhesive layer surface or bonding interface. Therefore, after using a reactive emulsifier, the emulsion particle size is smaller, the centrifugal stability is better, and the high-temperature holding power and anti-residue properties of the pressure-sensitive adhesive are further improved.

[0030] (9) In the preferred embodiment, the modified C5 petroleum resin emulsion prepared by using maleic anhydride-grafted C5 petroleum resin, functionalized shell monomer and reactive emulsifier can achieve a comprehensive improvement in emulsion stability, thickening performance, tack-holding performance, high temperature retention performance and anti-residue performance without significantly increasing the complexity of the process.

[0031] (10) The present invention has low cost, does not require complex equipment, and is suitable for application on the basis of existing water-based pressure-sensitive adhesive and tackifying resin emulsion production processes, and has good industrial applicability. Detailed Implementation

[0032] The present invention will be further described below with reference to the embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the raw materials used in the embodiments can be commercially available industrial products.

[0033] The main sources of raw materials are shown in Table 1: Table 1

[0034] The performance testing methods are shown in Table 2: Table 2

[0035] It should be noted that the visual criteria for the above-mentioned damage modes are as follows: After the 180° peel strength test, the appearance of the substrate surface and the PET film adhesive layer surface were observed, with the peel test area used as the observation area for judgment. During observation, the substrate surface was placed against a white background, and the presence of adhesive residue, adhesive spots, adhesive threads, or continuous adhesive film was observed from the front and sides. At the same time, the continuity and integrity of the adhesive layer on the PET film were observed, as well as whether there were any breaks, missing adhesive, or tearing.

[0036] When the adhesive layer on the PET base film remains largely continuous and intact, with virtually no adhesive residue on the surface of the substrate, or only a few small dot-like marks, and the peeling mainly occurs at the interface between the adhesive layer and the substrate, it is considered interface failure. Interface failure typically manifests as the adhesive layer peeling off entirely along with the PET base film, leaving the substrate surface relatively clean, indicating insufficient interfacial adhesion between the adhesive layer and the substrate.

[0037] When the adhesive layer on the PET base film shows obvious cracks, missing adhesive, or tearing, and corresponding adhesive residue is also present on the surface of the substrate, it indicates that the adhesive layer has been pulled apart from the inside during peeling, which is called cohesive failure. Cohesive failure usually manifests as a portion of the adhesive layer remaining on the PET base film, while another portion transfers to the surface of the substrate. This indicates that the interfacial adhesion between the adhesive layer and the substrate is strong, and the failure during peeling mainly occurs within the adhesive layer.

[0038] When a large area of ​​continuous adhesive residue, obvious adhesive spots, or stringy residue exists on the surface of the substrate, and the proportion of the residual adhesive layer covering the peel test area is high, it is considered severe adhesive residue. Severe adhesive residue can be regarded as a serious migration phenomenon after the internal damage of the adhesive layer, which usually indicates insufficient cohesive retention capacity of the adhesive layer or significant softening and migration of the adhesive layer. For ease of visual judgment, when the area of ​​residual adhesive on the surface of the substrate reaches or exceeds 50% of the peel test area, or when the residual adhesive is continuously distributed along the peel direction and accompanied by obvious stickiness and stringiness, it is judged as severe adhesive residue.

[0039] For visual assessment of residual adhesive area, the peel test area can be roughly divided into several equal-length regions along the peel direction. The residual adhesive coverage in each region can be observed, and the proportion of the total residual adhesive area to the peel test area can be estimated. If there is essentially no continuous residual adhesive on the surface of the substrate, and the adhesive layer is mainly intact on the PET base film, it is considered interfacial damage. If there is adhesive residue on both the surface of the substrate and the surface of the PET base film, and the adhesive layer on the PET base film is broken or missing, it is considered cohesive damage. If the residual adhesive area on the surface of the substrate is large and forms a continuous adhesive film or obvious adhesive spots, it is considered severe residual adhesive.

[0040] Preparation Example 1 The specific steps for preparing acrylate copolymer emulsions are as follows: (1) Add 100g of deionized water and 2.5g of compound emulsifier to a 500mL three-necked flask. The compound emulsifier consists of emulsifier A501 and emulsifier CO436 in a mass ratio of 1:1. Start stirring at 500rpm. After stirring for 5 minutes, slowly add a mixture of monomers consisting of 25g of methyl methacrylate, 50g of butyl acrylate, and 25g of isooctyl acrylate. After the mixture of monomers has been added, continue stirring for 30 minutes to obtain a pre-emulsion.

[0041] (2) Add 80g of deionized water, 1g of compound emulsifier and 0.5g of sodium bicarbonate to a 500mL four-necked flask. The compound emulsifier is composed of emulsifier A501 and emulsifier CO436 in a mass ratio of 1:1. The four-necked flask is connected to a mechanical stirrer, a condenser, a thermometer and a dropping device. Start stirring at 300rpm and heat to 85℃.

[0042] After the system temperature stabilizes, add 10 mL of the pre-emulsion obtained in step (1) to the four-necked flask, and then add 0.5 g of ammonium persulfate aqueous solution, which is prepared by dissolving 0.5 g of ammonium persulfate in 5 g of deionized water. After the addition is complete, react at 85 °C for 30 minutes to obtain the seed emulsion.

[0043] (3) Add 0.15 g of n-dodecyl mercaptan to the remaining pre-emulsion obtained in step (1), stir evenly, and use it as the pre-emulsion to be added dropwise. Add this pre-emulsion to be added dropwise evenly to the seed emulsion obtained in step (2) over 4 hours; at the same time, add 0.5 g of ammonium persulfate aqueous solution, which is prepared by dissolving 0.5 g of ammonium persulfate in 10 g of deionized water. During the dropwise addition, control the reaction temperature at 85°C and maintain the stirring speed at 300 rpm.

[0044] After the addition was complete, the system was heated to 90°C and the reaction was continued for 2 hours to allow the remaining monomers to react further. After the reaction was completed, the mixture was cooled to room temperature, and the pH was adjusted to 7.0-7.5 with ammonia. The mixture was then filtered through a 300-mesh filter cloth to obtain an acrylate copolymer emulsion with a solid content of 50.2%.

[0045] Example 1 A method for preparing a modified C5 petroleum resin emulsion, the specific steps of which are as follows: (1) Place 100g of hydrogenated C5 petroleum resin H5-1000W (softening point 100℃) in a 500mL three-necked flask, heat to 150℃, and turn on mechanical stirring at 300rpm to completely melt it. Add 2g of dibutyl phthalate and 5g of compound emulsifier in sequence. The compound emulsifier is composed of Span-80, Tween-80 and SDS in a mass ratio of 1.5:1.5:0.5. Stir evenly and cool to 85℃. Mix and dissolve 8g of butyl acrylate, 12g of methyl methacrylate and 0.2g of benzoyl peroxide and add it to the mixture. Stir evenly to obtain molten resin. (Note: Step (2) should be carried out immediately after adding the monomer. The whole process should be completed within 30 minutes to avoid premature polymerization of the monomer.) (2) Add 2g of polyvinyl alcohol 1788 to 80mL of deionized water and heat to 85℃ to dissolve, obtaining a protective colloidal aqueous solution. Slowly add it to the molten resin in step (1) through a constant pressure funnel over 10 minutes, while increasing the stirring speed to 1000rpm. After the system turns into a milky white liquid, slowly add 20mL of deionized water and continue stirring for 20 minutes to form a primary emulsion.

[0046] (3) The primary emulsion was transferred to a reactor equipped with a condenser and nitrogen protection, heated to 90°C, and kept at that temperature for 6 hours. After cooling to room temperature, the pH was adjusted to 7.0-7.5 with ammonia water, and the mixture was filtered through a 300-mesh filter cloth to obtain modified C5 petroleum resin emulsion E1.

[0047] The emulsion prepared in this embodiment has an E1 solid content of 60.5%, a viscosity of 580 mPa·s, and an average particle size of 285 nm.

[0048] Example 2 A method for preparing a modified C5 petroleum resin emulsion, the specific steps of which are as follows: (1) Place 100g of hydrogenated C5 petroleum resin H5-1150W (softening point 115℃) in a 500mL three-necked flask and heat to 150℃ at 300rpm until completely melted. Add 2g of dibutyl phthalate and 5g of compound emulsifier in sequence. The compound emulsifier is composed of Span-80, Tween-80 and SDS in a mass ratio of 1.5:1.5:0.5. Stir evenly and cool to 85℃. Add 12g of butyl acrylate, 18g of methyl methacrylate and 0.3g of benzoyl peroxide after mixing and dissolving, and stir evenly to obtain molten resin.

[0049] (2) Add 2g of polyvinyl alcohol 1799 to 80mL of deionized water and heat to 85°C to dissolve. Perform reverse emulsification according to the method in Example 1.

[0050] (3) Heat the primary emulsion to 90°C and keep it at that temperature for 6 hours. After cooling, adjust the pH, filter and discharge to obtain modified C5 petroleum resin emulsion E2.

[0051] The emulsion prepared in this embodiment has an E2 solid content of 61.9%, a viscosity of 610 mPa·s, and an average particle size of 305 nm.

[0052] Example 3 A method for preparing a modified C5 petroleum resin emulsion, the specific steps of which are as follows: (1) Place 100g of hydrogenated C5 petroleum resin H5-1250W (softening point 125℃) in a 500mL three-necked flask and heat to 150℃ at 300rpm until completely melted. Add 2g of dibutyl phthalate and 5g of compound emulsifier in sequence. The compound emulsifier is composed of Span-80, Tween-80 and SDS in a mass ratio of 1.5:1.5:0.5. Stir evenly and cool to 85℃. Add 8g of butyl acrylate, 12g of methyl methacrylate and 0.4g of benzoyl peroxide after mixing and dissolving, and stir evenly to obtain molten resin.

[0053] (2) Add 2g of polyvinyl alcohol 2099 to 80mL of deionized water and heat to 85°C to dissolve. Perform reverse emulsification according to the method in Example 1.

[0054] (3) Heat the primary emulsion to 90°C and keep it at that temperature for 5 hours. After cooling, adjust the pH, filter and discharge to obtain modified C5 petroleum resin emulsion E3.

[0055] The emulsion prepared in this embodiment has an E3 solid content of 62.1%, a viscosity of 540 mPa·s, and an average particle size of 280 nm.

[0056] Example 4 A method for preparing a modified C5 petroleum resin emulsion, the specific steps of which are as follows: (1) Prepare a mixture of molten resin and monomer according to the same raw material ratio as in step (1) of Example 1.

[0057] (2) Add 2g of polyvinyl alcohol 1799 to 80mL of deionized water and heat to 85℃ to dissolve. Slowly add the PVA aqueous solution to the molten resin over 10 minutes, increasing the stirring speed to 800rpm. After the system turns into a milky white liquid, turn on the ultrasonic generator and treat it for 15 minutes at an ultrasonic power of 400W. After the ultrasonic treatment is completed, slowly add 20mL of deionized water and continue stirring for 20 minutes to form a primary emulsion.

[0058] (3) Same as step (3) in Example 1, to obtain modified C5 petroleum resin emulsion E4.

[0059] The emulsion prepared in this embodiment has an E4 solid content of 61.7%, a viscosity of 490 mPa·s, and an average particle size of 210 nm.

[0060] Example 5 A method for preparing a modified C5 petroleum resin emulsion, the specific steps of which are as follows: (1) Place 100g of hydrogenated C5 petroleum resin H5-1150W (softening point 115℃) in a 500mL three-necked flask and heat to 155℃ at 300rpm until completely melted. Add 3g of dibutyl phthalate and 6g of compound emulsifier in sequence. The compound emulsifier is composed of Span-80, Tween-80 and SDS in a mass ratio of 2:1.5:0.5. Stir evenly and cool to 85℃. Add 8g of butyl acrylate, 12g of methyl methacrylate and 0.2g of benzoyl peroxide after mixing and dissolving, and stir evenly.

[0061] (2) Add 2.5g of polyvinyl alcohol 1788 to 80mL of deionized water and heat to 85°C to dissolve. Perform reverse emulsification according to the method in Example 1.

[0062] (3) Heat the primary emulsion to 90°C and keep it at that temperature for 6 hours. After cooling, adjust the pH, filter and discharge to obtain modified C5 petroleum resin emulsion E5.

[0063] The emulsion prepared in this embodiment has an E5 solid content of 61.3%, a viscosity of 530 mPa·s, and an average particle size of 290 nm.

[0064] Comparative Example 1 Commercially available ordinary C5 resin emulsion (non-core-shell structure) was selected and denoted as C1.

[0065] Specifically, we selected Tacolyn, sold by Synthomer Adhesive Technologies. TM 5085 ResinDispersion, as a commercially available common C5 petroleum resin emulsion, is designated as C1.

[0066] Comparative Example 2 Without adding any tackifying resin, it is designated as C2.

[0067] The acrylate copolymer emulsion obtained in Preparation Example 1 was used directly as the untackled control emulsion, denoted as C2. C2 does not contain C5 petroleum resin emulsion or other tackifying resins, and therefore does not have the core-shell structure with C5 petroleum resin as the core and polyacrylate copolymer as the shell as described in this invention.

[0068] Comparative Example 3 (1) Place 100g of hydrogenated C5 petroleum resin H5-1000W (softening point 100℃) in a 500mL three-necked flask, heat to 150℃, and turn on mechanical stirring at 300rpm to completely melt it. Add 2g of dibutyl phthalate and 5g of compound emulsifier in sequence. The compound emulsifier is composed of Span-80, Tween-80 and SDS in a mass ratio of 1.5:1.5:0.5. Stir evenly and cool to 85℃ to obtain molten resin.

[0069] Unlike Example 1, this comparative example does not include a shell monomer solution consisting of 8g butyl acrylate, 12g methyl methacrylate, and 0.2g benzoyl peroxide. Instead, the subsequent reverse emulsification step is performed directly. Therefore, this comparative example system does not contain shell monomers for forming the polyacrylate coating layer, nor does in-situ polymerization of acrylate monomers on or near the surface of C5 petroleum resin latex particles occur.

[0070] (2) Add 2g of polyvinyl alcohol 1788 to 80mL of deionized water and heat to 85℃ to dissolve, obtaining a protective colloidal aqueous solution. Slowly add it to the molten resin in step (1) through a constant pressure funnel over 10 minutes, while increasing the stirring speed to 1000rpm. After the system turns into a milky white liquid, slowly add 20mL of deionized water and continue stirring for 20 minutes to form a primary C5 petroleum resin emulsion.

[0071] (3) The primary C5 petroleum resin emulsion obtained in step (2) is transferred to a reactor equipped with a condenser and a nitrogen protection device, heated to 90°C, and kept at that temperature for 6 hours. After cooling to room temperature, the pH value is adjusted to 7.0-7.5 with ammonia water, and the emulsion is filtered through a 300-mesh filter cloth to obtain a non-core-shell C5 petroleum resin emulsion, which is designated as C3.

[0072] The C3 obtained in this comparative example had a solid content of 58.0%. Since butyl acrylate, methyl methacrylate, and benzoyl peroxide were not added to the C3, and no polyacrylate interfacial coating phase was present, it did not possess the core-shell structure described in this invention, which uses C5 petroleum resin as the main core phase and polyacrylate copolymer as the interfacial coating phase.

[0073] Preparation Example 2 The preparation method of the acrylic adhesive layer test sample, by weight, is as follows: For Examples 1-5, Comparative Examples 1 and 3, 15 parts of the modified C5 petroleum resin emulsions E1-E5, commercially available ordinary C5 resin emulsion C1, and non-core-shell C5 petroleum resin emulsion C3 prepared in Examples 1-5 were taken by dry weight and slowly added to 100 parts of the acrylate copolymer emulsion obtained in Preparation Example 1 under stirring at 300 rpm, and stirring was continued for 20 minutes; then 0.3 parts of wetting agent BYK-347 and 0.1 parts of defoamer BYK-024 were added in sequence, and stirring was carried out for 15 minutes to obtain the corresponding acrylate adhesive coating liquids.

[0074] For Comparative Example 2, take 100 parts of C2 directly, add 0.3 parts of wetting agent BYK-347 and 0.1 parts of defoamer BYK-024 in sequence while stirring at 300 rpm, stir for 15 minutes to obtain an untackified acrylic adhesive coating liquid.

[0075] Application: The above coating solutions were coated onto 50μm PET films with a wet film thickness of 80μm. The films were dried at 105℃ for 3 minutes, and then bonded with release paper to form water-based acrylic pressure-sensitive adhesive test samples. The samples were then cured at 23℃ and 50%RH for 24 hours before performance testing.

[0076] Performance testing The performance of each acrylic adhesive layer prepared above was tested. The performance testing methods are shown in Table 2, and the performance test results are summarized in Table 3.

[0077] Table 3

[0078] As shown in the test results of Examples 1-5, after using the modified C5 petroleum resin emulsion of the present invention, the annular initial tack of the waterborne acrylic pressure-sensitive adhesive test samples reached 10.8-13.2 N / 25 mm, the holding power exceeded 48 hours, and the 180° peel strength was between 13.6-14.8 N / 25 mm, all exhibiting cohesive failure after peeling. These results indicate that the core-shell structure modified C5 petroleum resin emulsion prepared by the method of the present invention can improve the initial tack and peel strength of the adhesive layer and form a strong interfacial adhesion between the adhesive layer and the substrate; simultaneously, the holding power remains above 48 hours, indicating that the emulsion of the present invention does not significantly weaken the static shear retention capacity of the adhesive layer.

[0079] Comparative Example 1 used a commercially available ordinary non-core-shell C5 resin emulsion. Although its 180° peel strength was 12.5 N / 25 mm and its initial tack was 11.5 N / 25 mm, indicating that the ordinary C5 resin emulsion had a certain tackifying effect, its holding power was only 3.5 hours, and serious residue was found after peeling, indicating that the ordinary C5 resin emulsion easily leads to softening, migration, or decreased cohesive retention of the adhesive layer. Comparative Example 2 was a control sample of untackified waterborne acrylic pressure-sensitive adhesive. Its initial tack was only 4.2 N / 25 mm, and its 180° peel strength was only 8.2 N / 25 mm, and the failure mode was interfacial failure, indicating that without the addition of tackifying resin, the acrylic adhesive layer had insufficient interfacial adhesion to the substrate. Comparative Example 3 used a non-core-shell C5 petroleum resin emulsion as a tackifying emulsion, and its initial tack was 10.5 N / 25 mm, which was higher than that of Comparative Example 2, indicating that the simply emulsified C5 petroleum resin still has a certain tackifying effect; however, its holding power was only 7.6 hours, and its 180° peel strength was only 9.6 N / 25 mm, and the failure mode was interfacial failure, which was significantly lower than that of Examples 1-5. This result shows that the non-core-shell C5 petroleum resin emulsion obtained by only phase inversion emulsification cannot form a polyacrylate interfacial coating phase on the surface or near-surface region of C5 petroleum resin latex particles, and therefore it is difficult to fully improve its compatibility and interfacial adhesion with the acrylate copolymer emulsion, nor can it achieve a synergistic improvement in initial tack, peel strength and holding power.

[0080] To further improve the compatibility between the modified C5 petroleum resin emulsion and the acrylate copolymer emulsion, and to reduce the migration tendency of C5 petroleum resin in the adhesive layer, this invention can further modify the C5 petroleum resin core phase and the polyacrylate shell phase. Specifically, maleic anhydride is first used to lightly graft hydrogenated C5 petroleum resin, introducing a small amount of anhydride groups and / or carboxyl groups into the C5 petroleum resin molecules; then, a small amount of glycidyl methacrylate and / or hydroxyethyl methacrylate is added to the shell monomer, giving the formed polyacrylate shell phase a certain degree of polarity and reactivity. Through the above method, the bonding force between the C5 petroleum resin core phase and the polyacrylate shell phase can be improved, resulting in better stability of the emulsion after blending with the acrylate copolymer emulsion, and further improving the holding power and anti-residue properties of the pressure-sensitive adhesive.

[0081] Example 6 A method for preparing a modified C5 petroleum resin emulsion, the specific steps of which are as follows: (1) Add 100g of hydrogenated C5 petroleum resin H5-1150W (softening point 115℃) to a 500mL four-necked flask. Connect the four-necked flask to a mechanical stirrer, thermometer, condenser, and nitrogen inlet device. Heat to 170℃ under nitrogen protection, start stirring at 300rpm to completely melt the resin. Then add 1.5g of maleic anhydride and 0.15g of dicumyl peroxide, and keep the reaction at 170℃ for 2 hours.

[0082] After the reaction was completed, the mixture was subjected to reduced pressure at 140-150℃ for 30 minutes to remove unreacted maleic anhydride and a small amount of low-boiling substances, yielding maleic anhydride-grafted C5 petroleum resin. The acid value of the obtained maleic anhydride-grafted C5 petroleum resin was 9.8 mgKOH / g, as determined by acid value testing.

[0083] (2) Take 100g of the maleic anhydride-grafted C5 petroleum resin obtained in step (1) and place it in a 500mL three-necked flask. Heat it to 155℃ and let it melt completely. Add 2g of tributyl acetylacetic acid and 5g of compound emulsifier in sequence. The compound emulsifier is composed of Span-80, Tween-80 and SDS in a mass ratio of 1.5:1.5:0.5. Stir evenly and then cool to 85℃.

[0084] 8g butyl acrylate, 12g methyl methacrylate, 1.5g glycidyl methacrylate and 0.25g benzoyl peroxide were mixed and dissolved, and then added to the above molten resin system. The mixture was stirred for 15 minutes to obtain a mixture of molten resin and shell monomer.

[0085] (3) Add 2g of polyvinyl alcohol 1799 to 85g of deionized water and heat to 85℃ to dissolve, obtaining a protective colloidal aqueous solution. Slowly add this protective colloidal aqueous solution to the mixture of molten resin and shell monomer obtained in step (2) through a constant pressure funnel over 10-15 minutes, while increasing the stirring speed to 1000rpm. After the system gradually changes from a viscous oil phase to a milky white emulsion, slowly add 20g of deionized water and continue stirring for 20 minutes to obtain a primary emulsion.

[0086] (4) The primary emulsion obtained in step (3) is transferred to a reactor equipped with a condenser and a nitrogen protection device, heated to 90°C, and kept at that temperature for 6 hours to allow the shell monomers to polymerize on the surface or near the surface of the maleic anhydride-grafted C5 petroleum resin latex particles. After the reaction is complete, the mixture is cooled to room temperature, the pH is adjusted to 7.0-7.5 with ammonia, and the mixture is filtered through a 300-mesh filter cloth to obtain modified C5 petroleum resin emulsion E6.

[0087] The emulsion prepared in this embodiment has an E6 solid content of 62.0%, a viscosity of 575 mPa·s at 25°C, an average particle size of 265 nm, and no obvious stratification was observed after centrifugation at 3000 rpm for 30 minutes.

[0088] Example 7 A method for preparing a modified C5 petroleum resin emulsion, the specific steps of which are as follows: This embodiment is basically the same as Example 6, except that in step (2), the shell monomer is composed of 10g butyl acrylate, 12g methyl methacrylate, 1.0g glycidyl methacrylate, 1.0g hydroxyethyl methacrylate and 0.28g benzoyl peroxide. Other raw materials and process conditions are the same as in Example 6, and modified C5 petroleum resin emulsion E7 is obtained.

[0089] The emulsion prepared in this embodiment has an E7 solid content of 62.4%, a viscosity of 610 mPa·s at 25°C, an average particle size of 278 nm, and no obvious stratification was observed after centrifugation at 3000 rpm for 30 minutes.

[0090] Example 8 A method for preparing a modified C5 petroleum resin emulsion, the specific steps of which are as follows: This embodiment is basically the same as Example 6, except that: in step (1), the amount of maleic anhydride used is 2.0g, the amount of dicumyl peroxide used is 0.2g, and the acid value of the resulting maleic anhydride-grafted C5 petroleum resin is 13.5mgKOH / g; in step (2), the shell monomer is composed of 8g butyl acrylate, 14g methyl methacrylate, 2.0g glycidyl methacrylate and 0.3g benzoyl peroxide. Other raw materials and process conditions are the same as in Example 6, and modified C5 petroleum resin emulsion E8 is obtained.

[0091] The emulsion E8 prepared in this embodiment has a solid content of 62.8%, a viscosity of 640 mPa·s at 25°C, an average particle size of 285 nm, and no obvious stratification was observed after centrifugation at 3000 rpm for 30 minutes.

[0092] Example 9 A method for preparing a modified C5 petroleum resin emulsion, the specific steps of which are as follows: (1) Add 100g of hydrogenated C5 petroleum resin H5-1150W (softening point 115℃) to a 500mL four-necked flask. Connect the four-necked flask to a mechanical stirrer, thermometer, condenser, and nitrogen inlet device. Heat to 170℃ under nitrogen protection, start stirring at 300rpm to completely melt the resin. Then add 1.5g of maleic anhydride and 0.15g of dicumyl peroxide, and keep the reaction at 170℃ for 2 hours.

[0093] After the reaction was completed, the mixture was subjected to reduced pressure at 140-150℃ for 30 minutes to remove unreacted maleic anhydride and a small amount of low-boiling substances, yielding maleic anhydride-grafted C5 petroleum resin. The acid value of the obtained maleic anhydride-grafted C5 petroleum resin was 9.8 mgKOH / g, as determined by acid value testing.

[0094] (2) Take 100g of the maleic anhydride-grafted C5 petroleum resin obtained in step (1) and place it in a 500mL three-necked flask. Heat it to 155℃ to completely melt it. Add 2g of tributyl acetylacetic acid, 4g of compound emulsifier and 1g of reactive emulsifier in sequence. The compound emulsifier is composed of Span-80, Tween-80 and SDS in a mass ratio of 1.5:1.5:0.5. The reactive emulsifier is ELEMINOL JS-20 produced by Sanyo Chemical Industries, Ltd. After the above materials are added, stir at 300rpm for 10 minutes to evenly disperse the emulsifier in the molten resin, and then cool it to 85℃.

[0095] After mixing and dissolving 10g butyl acrylate, 12g methyl methacrylate, 1.0g glycidyl methacrylate, 1.0g hydroxyethyl methacrylate and 0.28g benzoyl peroxide, the mixture was slowly added to the above molten resin system and stirred for 15 minutes to obtain a mixture of molten resin and shell monomer.

[0096] (3) Add 2g of polyvinyl alcohol 1799 to 85g of deionized water and heat to 85℃ to dissolve, obtaining a protective colloidal aqueous solution. Slowly add this protective colloidal aqueous solution to the molten resin and shell monomer mixture obtained in step (2) through a constant pressure funnel over 10-15 minutes, while simultaneously increasing the stirring speed to 1000rpm. During the addition process, the system gradually changes from a viscous oil phase to a milky white emulsion. After the phase transition is complete, slowly add 20g of deionized water and continue stirring for 20 minutes to obtain a primary emulsion.

[0097] (4) The primary emulsion obtained in step (3) is transferred to a reactor equipped with a condenser and a nitrogen protection device, heated to 90°C, and kept at that temperature for 6 hours to allow the shell monomers to polymerize on the surface or near the surface of the maleic anhydride-grafted C5 petroleum resin latex particles. After the reaction is complete, the mixture is cooled to room temperature, the pH is adjusted to 7.0-7.5 with ammonia, and the mixture is filtered through a 300-mesh filter cloth to obtain modified C5 petroleum resin emulsion E9.

[0098] The emulsion E9 prepared in this embodiment has a solid content of 62.5%, a viscosity of 590 mPa·s at 25°C, an average particle size of 245 nm, and no obvious stratification was observed after centrifugation at 3000 rpm for 30 minutes.

[0099] Comparative Example 4 A method for preparing a modified C5 petroleum resin emulsion, the specific steps of which are as follows: (1) Place 100g of ungrafted hydrogenated C5 petroleum resin H5-1150W (softening point 115℃) in a 500mL three-necked flask, heat to 155℃, and turn on mechanical stirring at 300rpm to completely melt it. Add 2g of acetylacetic acid tributyl ester and 5g of compound emulsifier in sequence. The compound emulsifier is composed of Span-80, Tween-80 and SDS in a mass ratio of 1.5:1.5:0.5. After stirring evenly, cool to 85℃.

[0100] After mixing and dissolving 8g butyl acrylate, 12g methyl methacrylate, 1.5g glycidyl methacrylate and 0.25g benzoyl peroxide, the mixture was added to the above molten resin system and stirred for 15 minutes to obtain a mixture of molten resin and shell monomer.

[0101] (2) Add 2g of polyvinyl alcohol 1799 to 85g of deionized water and heat to 85℃ to dissolve, obtaining a protective colloidal aqueous solution. Slowly add this protective colloidal aqueous solution to the mixture of molten resin and shell monomer obtained in step (1) through a constant pressure funnel over 10-15 minutes, while increasing the stirring speed to 1000rpm. After the system gradually changes from a viscous oil phase to a milky white emulsion, slowly add 20g of deionized water and continue stirring for 20 minutes to obtain a primary emulsion.

[0102] (3) The primary emulsion obtained in step (2) is transferred to a reactor equipped with a condenser and a nitrogen protection device, heated to 90°C, and kept at that temperature for 6 hours. After the reaction is completed, it is cooled to room temperature, the pH value is adjusted to 7.0-7.5 with ammonia, and filtered through a 300-mesh filter cloth to obtain modified C5 petroleum resin emulsion C4.

[0103] The emulsion prepared in this comparative example had a C4 solid content of 61.5%, a viscosity of 650 mPa·s at 25°C, an average particle size of 310 nm, and slight sedimentation after centrifugation at 3000 rpm for 30 minutes.

[0104] The main difference between this comparative example and Example 6 is that the hydrogenated C5 petroleum resin was not grafted with maleic anhydride in this comparative example. The C5 petroleum resin lacks anhydride groups and / or carboxyl groups, so its interaction with the polyacrylate shell containing glycidyl methacrylate is weaker.

[0105] Comparative Example 5 A method for preparing a modified C5 petroleum resin emulsion, the specific steps of which are as follows: (1) Add 100g of hydrogenated C5 petroleum resin H5-1150W (softening point 115℃) to a 500mL four-necked flask. Connect the four-necked flask to a mechanical stirrer, thermometer, condenser, and nitrogen inlet device. Heat to 170℃ under nitrogen protection, start stirring at 300rpm to completely melt the resin. Then add 1.5g of maleic anhydride and 0.15g of dicumyl peroxide, and keep the reaction at 170℃ for 2 hours.

[0106] After the reaction was completed, the mixture was subjected to reduced pressure at 140-150℃ for 30 minutes to remove unreacted maleic anhydride and a small amount of low-boiling substances, yielding maleic anhydride-grafted C5 petroleum resin. The acid value of the obtained maleic anhydride-grafted C5 petroleum resin was 9.8 mgKOH / g, as determined by acid value testing.

[0107] (2) Take 100g of the maleic anhydride-grafted C5 petroleum resin obtained in step (1) and place it in a 500mL three-necked flask. Heat it to 155℃ and let it melt completely. Add 2g of tributyl acetylacetic acid and 5g of compound emulsifier in sequence. The compound emulsifier is composed of Span-80, Tween-80 and SDS in a mass ratio of 1.5:1.5:0.5. Stir evenly and then cool to 85℃.

[0108] 10g of butyl acrylate, 12g of methyl methacrylate and 0.28g of benzoyl peroxide were mixed and dissolved, and then added to the above molten resin system. The mixture was stirred for 15 minutes to obtain a mixture of molten resin and shell monomer.

[0109] (3) Add 2g of polyvinyl alcohol 1799 to 85g of deionized water and heat to 85℃ to dissolve, obtaining a protective colloidal aqueous solution. Slowly add this protective colloidal aqueous solution to the mixture of molten resin and shell monomer obtained in step (2) through a constant pressure funnel over 10-15 minutes, while increasing the stirring speed to 1000rpm. After the system gradually changes from a viscous oil phase to a milky white emulsion, slowly add 20g of deionized water and continue stirring for 20 minutes to obtain a primary emulsion.

[0110] (4) The primary emulsion obtained in step (3) is transferred to a reactor equipped with a condenser and a nitrogen protection device, heated to 90°C, and kept at that temperature for 6 hours. After the reaction is completed, it is cooled to room temperature, the pH value is adjusted to 7.0-7.5 with ammonia, and filtered through a 300-mesh filter cloth to obtain modified C5 petroleum resin emulsion.

[0111] The emulsion prepared in this comparative example had a C5 solid content of 62.0%, a viscosity of 620 mPa·s at 25°C, an average particle size of 295 nm, and no obvious stratification was observed after centrifugation at 3000 rpm for 30 minutes.

[0112] The main difference between this comparative example and Example 7 is that glycidyl methacrylate and hydroxyethyl methacrylate were not added to the shell monomers in this comparative example. As a result, the polyacrylate shell lacks epoxy and hydroxyl functional sites, and therefore the interfacial bonding force between it and maleic anhydride-grafted C5 petroleum resin is weak.

[0113] Comparative Example 6 A method for preparing a modified C5 petroleum resin emulsion, the specific steps of which are as follows: (1) Add 100g of hydrogenated C5 petroleum resin H5-1150W (softening point 115℃) to a 500mL four-necked flask. Connect the four-necked flask to a mechanical stirrer, thermometer, condenser, and nitrogen inlet device. Heat to 170℃ under nitrogen protection, start stirring at 300rpm to completely melt the resin. Then add 1.5g of maleic anhydride and 0.15g of dicumyl peroxide, and keep the reaction at 170℃ for 2 hours.

[0114] After the reaction was completed, the mixture was subjected to reduced pressure at 140-150℃ for 30 minutes to remove unreacted maleic anhydride and a small amount of low-boiling substances, yielding maleic anhydride-grafted C5 petroleum resin. The acid value of the obtained maleic anhydride-grafted C5 petroleum resin was 9.8 mgKOH / g, as determined by acid value testing.

[0115] (2) Take 100g of the maleic anhydride-grafted C5 petroleum resin obtained in step (1) and place it in a 500mL three-necked flask. Heat it to 155℃ and let it melt completely. Add 2g of tributyl acetylacetic acid and 5g of compound emulsifier in sequence. The compound emulsifier is composed of Span-80, Tween-80 and SDS in a mass ratio of 1.5:1.5:0.5. Stir evenly and then cool to 85℃.

[0116] After mixing and dissolving 10g butyl acrylate, 12g methyl methacrylate, 1.0g glycidyl methacrylate, 1.0g hydroxyethyl methacrylate and 0.28g benzoyl peroxide, the mixture was added to the above molten resin system and stirred for 15 minutes to obtain a mixture of molten resin and shell monomer.

[0117] (3) Add 2g of polyvinyl alcohol 1799 to 85g of deionized water and heat to 85℃ to dissolve, obtaining a protective colloidal aqueous solution. Slowly add this protective colloidal aqueous solution to the mixture of molten resin and shell monomer obtained in step (2) through a constant pressure funnel over 10-15 minutes, while increasing the stirring speed to 1000rpm. After the system gradually changes from a viscous oil phase to a milky white emulsion, slowly add 20g of deionized water and continue stirring for 20 minutes to obtain a primary emulsion.

[0118] (4) The primary emulsion obtained in step (3) is transferred to a reactor equipped with a condenser and a nitrogen protection device, heated to 90°C, and kept at that temperature for 6 hours. After the reaction is completed, it is cooled to room temperature, the pH value is adjusted to 7.0-7.5 with ammonia, and filtered through a 300-mesh filter cloth to obtain modified C5 petroleum resin emulsion C6.

[0119] The emulsion prepared in this comparative example had a C6 solid content of 62.2%, a viscosity of 685 mPa·s at 25°C, an average particle size of 320 nm, and slight sedimentation after centrifugation at 3000 rpm for 30 minutes.

[0120] The main difference between this comparative example and Example 9 is that this comparative example did not include a reactive emulsifier, while Example 9 included ELEMINOL JS-20 manufactured by Sanyo Chemical Industries, Ltd. Compared to emulsion systems using only Span-80, Tween-80, and SDS, reactive emulsifiers can participate in the interfacial polymerization of latex particles, helping to reduce the adverse effects of free emulsifiers on emulsion stability and adhesive layer tackiness.

[0121] Preparation Example 3 The preparation method of the acrylic adhesive layer test sample, by weight, is as follows: For Examples 6-9 and Comparative Examples 4-6, 15 parts of the modified C5 petroleum resin emulsions E6-E9 prepared in Examples 6-9 and C4-C6 prepared in Comparative Examples 4-6 were taken by dry weight and slowly added to 100 parts of the acrylate copolymer emulsion obtained in Preparation Example 1 under stirring at 300 rpm. The stirring was continued for 20 minutes. Then, 0.3 parts of wetting agent BYK-347 and 0.1 parts of defoamer BYK-024 were added in sequence and stirred for 15 minutes to obtain the corresponding acrylate adhesive coating liquids.

[0122] Application: The above coating solutions were coated onto 50μm PET films with a wet film thickness of 80μm. The films were dried at 105℃ for 3 minutes, and then bonded with release paper to form water-based acrylic pressure-sensitive adhesive test samples. The samples were then cured at 23℃ and 50%RH for 24 hours before performance testing.

[0123] Performance testing The acrylic adhesive layer test samples obtained in Examples 6-9 and Comparative Examples 4-6 were subjected to performance tests. The performance test methods are shown in Table 2, and the performance test results are summarized in Table 3.

[0124] Table 3

[0125] analyze: The further modified C5 petroleum resin emulsions obtained in Examples 6-9 had a solid content of 62.0-62.8%, a viscosity of 575-640 mPa·s at 25°C, an average particle size of 245-285 nm, and good centrifugal stability. This indicates that after introducing a small amount of maleic anhydride graft structure into the C5 petroleum resin and adding a small amount of functional monomers to the shell layer, the emulsion still has good preparation stability and use stability.

[0126] Table 3 shows that the initial tack of the waterborne acrylic pressure-sensitive adhesive samples obtained in Examples 6-9 was 12.7-13.3 N / 25 mm, the 180° peel strength was 14.5-15.0 N / 25 mm, the holding power exceeded 72 hours, the holding power at 70°C reached 18.5-24.0 hours, and the residual adhesive area was no more than 8%. Compared with Examples 1-5, Examples 6-9 maintained high levels of initial tack and peel strength while further improving holding power, 70°C holding power, and residual adhesive performance. These results indicate that the combination of maleic anhydride-grafted C5 petroleum resin with a polyacrylate shell containing glycidyl methacrylate and / or hydroxyethyl methacrylate is beneficial for improving the compatibility and cohesive retention of the C5 petroleum resin emulsion and the acrylic adhesive layer system.

[0127] Comparative Example 4 did not use maleic anhydride-grafted C5 petroleum resin. Although glycidyl methacrylate was still added as a shell functional monomer, the binding force between the core and shell phases was weaker due to the lack of anhydride and / or carboxyl groups in the C5 petroleum resin itself. Its holding power, 70°C holding power, and anti-residue properties were significantly lower than those of Examples 6-9. This result indicates that maleic anhydride grafting modification has a positive effect on improving the migration resistance and tack retention properties of C5 petroleum resin emulsions.

[0128] Although Comparative Example 5 used maleic anhydride-grafted C5 petroleum resin, it did not contain glycidyl methacrylate and hydroxyethyl methacrylate in the shell layer. The resulting adhesive layer still exhibited significantly lower tack holding power and anti-residue properties at 70°C compared to Examples 6-9. This result indicates that the shell functional monomers play a crucial role in improving the core-shell interface bonding and enhancing the cohesive retention capacity of the adhesive layer.

[0129] Comparative Example 6, without the addition of a reactive emulsifier, resulted in an emulsion with a larger particle size, slight sedimentation after centrifugation, and lower residual adhesive area and 70°C holding power compared to Example 9. These results indicate that reactive emulsifiers can improve emulsion stability and help reduce the adverse effects of free emulsifiers on adhesive holding power and residual adhesive properties.

[0130] In summary, the further modification scheme, through the synergy of maleic anhydride-grafted C5 petroleum resin, shell functional monomers, and reactive emulsifiers, further improves the emulsion stability, high-temperature tack resistance, and residue resistance of the modified C5 petroleum resin emulsion without significantly increasing process complexity. The raw materials required for this scheme are readily available, and the process conditions are essentially the same as in Examples 1-5, making it suitable for widespread application in existing water-based pressure-sensitive adhesive production processes.

[0131] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a modified C5 petroleum resin emulsion, characterized in that, Includes the following steps: C5 petroleum resin is heated, plasticizer and emulsifier are added, stirred evenly and cooled, then shell monomer solution is added and stirred evenly to obtain a mixture of molten resin and shell monomer; wherein, the shell monomer solution includes monomer and initiator; A protective colloid aqueous solution is slowly added to the mixture of molten resin and shell monomer, and the stirring speed is increased to carry out phase transition emulsification. After the system undergoes phase transition, deionized water is added and stirring is continued to form a primary emulsion. The protective colloid aqueous solution includes polyvinyl alcohol. The primary emulsion was heated under inert gas protection, kept at that temperature for reaction, cooled, and then the pH value was adjusted and filtered to obtain a modified C5 petroleum resin emulsion.

2. The method for preparing the modified C5 petroleum resin emulsion according to claim 1, characterized in that, The C5 petroleum resin includes hydrogenated C5 petroleum resin and / or modified C5 petroleum resin, wherein the softening point of the hydrogenated C5 petroleum resin is 100-125℃.

3. The method for preparing the modified C5 petroleum resin emulsion according to claim 1, characterized in that, The plasticizer includes one or more of dibutyl phthalate, tributyl acetyl citrate, tributyl citrate, epoxidized soybean oil, hydrogenated naphthenic oil, polyether ester plasticizers, and low molecular weight polyisobutylene.

4. The method for preparing the modified C5 petroleum resin emulsion according to claim 1, characterized in that, The emulsifier includes one or more of Span-80, Tween-80, sodium dodecyl sulfate, and reactive emulsifiers.

5. The method for preparing the modified C5 petroleum resin emulsion according to claim 1, characterized in that, The reverse emulsification is performed under ultrasonic conditions, with an ultrasonic power of 100-800W and an ultrasonic time of 5-60min.

6. The method for preparing the modified C5 petroleum resin emulsion according to claim 2, characterized in that, The preparation method of modified C5 petroleum resin includes the following steps: The C5 petroleum resin is heated to a molten state, and maleic anhydride and an initiator are added under inert gas protection. The reaction is carried out at 150-190℃ for 1-4 hours. After the reaction is completed, the resin is subjected to reduced pressure treatment at 140-150℃ to obtain the modified C5 petroleum resin.

7. The method for preparing the modified C5 petroleum resin emulsion according to claim 1 or 6, characterized in that, The initiator is one or more of dicumyl peroxide, benzoyl peroxide, azobisisobutyronitrile, and di-tert-butyl peroxide.

8. The method for preparing the modified C5 petroleum resin emulsion according to claim 1, characterized in that, The monomers include one or more of butyl acrylate, methyl methacrylate, glycidyl methacrylate, and hydroxyethyl methacrylate.

9. The method for preparing the modified C5 petroleum resin emulsion according to claim 4, characterized in that, The mass ratio of Span-80, Tween-80 and sodium dodecyl sulfate is (1-2):(1-2):(0.5-1).

10. A pressure-sensitive adhesive, characterized in that, The raw materials of the pressure-sensitive adhesive include at least one of modified C5 petroleum resin emulsion, acrylate copolymer emulsion, wetting agent, and defoamer, wherein the modified C5 petroleum resin emulsion is prepared by the preparation method of the modified C5 petroleum resin emulsion according to any one of claims 1-9.

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